Norfolk Island isn't Australia - you'll clear customs in Lord Howe both ways
I had a TSO'ed raft, which was borrowed (I paid to have it repacked which needs to be done every two years). You dont want a dodgey raft out there!
Nav in NZ is bog easy. Keep the water on one side and off you go
When are you thinking of going?
I dont recall there being any security issues at all, even at Christchurch or Dunedin. They just aren't as anal about it as we are (which is a refreshing change!)
Hell, once I even lost my passport on the plane going to NZ and they still let me in!